What you see through the rangefinder (in this case an M typ 262, but the M10 view is identical). The outer white lines mark what what will be captured with a 50mm lens attached, while the small central patch is used to set focus. The camera can display any of three pairs of frame lines corresponding to 28/90mm, 35/135mm, 50/75mm – using any other focal length requires an external viewfinder mounted in the hot-shoe.